Dual-loop cooling system

ABSTRACT

Disclosed are methods and apparatuses for cooling a work piece surface using a dual-loop cooling system. The system includes a vapor-compression loop and a liquid-evaporation loop. The loops are configured to prepare a coolant at or approximately at saturation for delivery into a chamber for cooling the surface. A preferred liquid-evaporation loop includes a chamber, a phase separator, a liquid pressurizer, and a vapor mixer that heats the coolant to or near its saturation temperature. A preferred vapor-compression loop includes the phase separator, a compressor, a condenser, an expansion valve, and a return line. The vapor mixer preferably heats the coolant by mixing liquid coolant with vapor coolant derived from the vapor-compression loop. A two-phase flow detector may be disposed downstream of the vapor mixer and be in communication with a vapor valve disposed upstream of the vapor mixer to ensure that an appropriate amount of vapor is fed into the vapor mixer to induce evaporation. Methods include cooling a surface by cycling a coolant through the liquid-evaporation loop and preparing the coolant at saturation with vapor derived from the vapor-compression loop.

FIELD OF THE INVENTION

The present invention is directed to methods and apparatuses for coolingwork pieces such as processors or other electronic devices.

BACKGROUND

Methods for maintaining electronic devices within a safe and desirableoperating temperature range have been a topic of research since theinvention of the transistor. Maintaining such a temperature range is achallenging problem that is only increasing in importance and difficultyas semiconductor technology continues to progress. State of the artmicroprocessors easily produce more than 40 W of thermal energy persquare centimeter of the microchip surface. Power electronics can attainheat densities three times this level.

In addition to the requirement to manage such high heat intensity, thereis a need to remove the thermal energy efficiently, both in terms ofenergy expended and space required. According to the Department ofEnergy, approximately 3% of electricity used in the United States isdevoted to powering data centers or computer facilities. Approximatelyhalf of this electricity goes toward power conditioning and cooling.Increasing the efficiency of cooling would lead to dramatic savings inenergy. More efficient cooling is also needed in transportation systemsdue to the rapidly increased adoption of hybrid and electric vehicles.More efficient cooling of the electronic systems in these vehiclestranslates into increased range and utility of the vehicles.

The majority of computer systems are currently cooled using air that isforced through a series of extended metal surfaces coupled to microchipsor other electronic work pieces. However, these systems are inherentlylimited in terms of their performance and efficiency. Due to the verylow volumetric heat capacity of air, a large volume of air flow isrequired to remove the heat load of even one processor. A recommendedvalue is 5 to 10 cubic feet per minute (cfm) per 100 W of heat load.This equates to the equivalent of two air conditioning systems sized fora typical U.S. house being required to cool a rack of computers. Atypical data center may have several hundred of these racks.

Furthermore, air-cooled systems are not only inefficient in themselvesbut also cause the electronics they cool to operate less efficiently.Because of the low thermal capacity of air, fully utilizedmicroprocessors operate at or near the maximum rated temperature.Reducing the temperature of microprocessors can save at least 25% of theenergy they consume at the same level of utilization.

Numerous liquid cooling schemes have been implemented to address some ofthe problems associated with air cooling. A majority rely on using waterthat flows through channels defined by fins, wherein the fins areindirectly coupled to a work piece via a metal base plate, a thermalpaste, and a direct bond metal such as copper. This approach can beeffective. However, the intervening materials between the water and thework piece induce significant thermal resistance, which reduces theefficiency of the system. In addition to the thermal resistance, theintervening materials add to the cost and time of manufacture,constitute additional points of failure, and provide possible disposalissues. Finally, the intervening materials render the system unable toefficiently deal with local hot spots on a work piece. The entire systemmust be designed to accommodate the maximum anticipated heat load of oneor a few localized hot spots.

Further improvements have been made to liquid-cooled systems by using acoolant other than water. Dielectric coolants can come into directcontact with the electronic devices and not harm them. Use of suchdielectric coolants permits eliminating a significant amount of thermalinterface material from the system. However, the dielectric coolants areless efficient coolants than water. More aggressive cooling techniquesare therefore required to achieve the necessary performance.

One approach with dielectric coolants includes direct spray impingement,in which atomized liquid coolant is sprayed directly on a work piecesurface through air or vapor. However, spray cooling is limited byseveral factors. First, spray cooling requires a significant workingvolume to enable the atomized sprays to form. Second, atomizing theliquid requires a significant amount of pressure upstream of theatomizer. The pressure is required to generate an appropriate pressuredrop at the atomizer-air interface. An appropriate pressure dropfacilitates atomization by inducing partial evaporation of coolant asthe coolant passes through the interface. Maintaining the amount ofpressure to ensure the appropriate pressure drop consumes a significantamount of energy. Third, high flow rates are required to preventcritical heat flux, wherein evaporation of coolant on the surfaceprevents atomized liquid from reaching the surface. In the end, it hasproven difficult to design a practical, compact spray cooling system,despite the large amount of effort that has been expended to do so.

Another approach is to use direct jet impingement, wherein streams ofliquid are projected through a liquid medium and impinge directly on awork piece surface. While impinging jets are known to have notable heattransfer performance, impinging jet systems have problems ofscalability. To achieve high heat transfer over a large area, arrays ofjets must be used. The use of arrays in conventional direct jetimpingement systems, however, is problematic. Opposing surface flow offluid from neighboring jet streams induces stagnant regions on thesurface. The heat transfer performance in these stagnant regions candrop to nearly zero. Furthermore, conventional jet impingement systemsuse nozzles that are part of a large, flat nozzle plate. As fluid fromjet streams impinging on the surface flow from the center of the plateflows outward, it can have enough momentum to completely deflect theoutermost jets, preventing them from impinging on the heated surface. Asa result of these factors, conventional impinging jet systems arelimited in size.

Direct impingement cooling is commonly employed in a vapor-compressioncooling cycle. The vapor-compression cooling cycle compresses vaporcoolant generated from cooling a surface, condenses the compressed vaporto a liquid while transferring the heat to an external temperature sink,expands the condensed coolant to cause a drop in pressure andtemperature, impinges the expanded coolant against the surface forcooling, and re-compresses the vapor generated therefrom and recycles itthrough the cycle. While vapor-compression cooling cycles are simple andthermodynamically ideal for generating atomized sprays, they are knownfor circulating oil derived from the condenser, do not operate well whencoupled to high temperature sinks, are difficult to adjust with changingheat sink temperatures, and do not provide redundancy within the system.

SUMMARY OF THE INVENTION

The present invention addresses the shortcomings of conventional coolingsystems by providing a dual-loop cooling system that provides at leasttwo, partially parallel cycles that prepare coolant at or approximatelyat saturation prior to using the coolant for cooling.

One aspect of the invention comprises an apparatus for cooling asurface. One version of the apparatus comprises at least one chamberwith the surface exposed therein. The chamber comprises an inlet and anoutlet and is configured for flowing fluid therethrough by enteringthrough the inlet in a stream projected against the surface and exitingthrough the outlet. The apparatus also comprises a liquid source influid communication with the inlet of the chamber. The apparatus alsocomprises a heat-transfer apparatus configured to transfer heat toliquid derived from the liquid source at a point upstream of the inlet.

The apparatus may further include a heat-transfer regulator configuredto adjust amount of heat transferred via the heat-transfer apparatus tothe liquid. The heat-transfer regulator may include a two-phase flowdetector disposed between the heat-transfer apparatus and the inlet,wherein the two-phase flow detector is configured to communicate with adevice that adjusts an amount of heat transferred via the heat-transferapparatus to the liquid in response to a signal indicating the presenceof two-phase flow, such as an amount of bubbles detected in the liquid.

In a preferred version of the invention, the heat-transfer apparatuscomprises a vapor mixer in fluid communication with the liquid sourceand a vapor source. A vapor valve configured to adjust flow of vapor tothe vapor mixer is disposed between the vapor mixer and the vaporsource. A two-phase flow detector in communication with the vapor valveis disposed between the vapor mixer and the inlet. The two-phase flowdetector is configured to communicate with the vapor valve to adjustflow of vapor to the vapor mixer in response to a signal indicating thepresence of two-phase flow.

In some versions of the invention, the vapor source comprises a phaseseparator and a compressor. The compressor is in fluid communicationwith the phase separator in a configuration to selectively receive vaportherefrom and is also in regulated fluid communication with the vapormixer to deliver compressed vapor thereto. Such a version may alsoinclude a condenser and an expansion valve to prepare substantiallysaturated coolant. The condenser is in fluid communication with thecompressor to receive fluid therefrom and is further in fluidcommunication with the phase separator via a return line in aconfiguration to deliver fluid thereto. The expansion valve is disposedbetween the condenser and the return line. The condenser may further bein regulated fluid communication with the inlet of the chamber todeliver fluid thereto. A circuit valve disposed between the expansionvalve and the inlet of the chamber adjusts flow of fluid from theexpansion valve to the inlet. The return line recycles to the phaseseparator fluid that is prevented from reaching the chamber when thecircuit valve is closed.

In some versions of the invention, the liquid source comprises a phaseseparator and a liquid pressurizer. The phase separator is in fluidcommunication with the outlet of the chamber and receives fluidtherefrom. The fluid pressurizer is in fluid communication with thephase separator in a configuration to selectively receive liquidtherefrom and is further in fluid communication with the heat-transferapparatus as well as the chamber inlet. An exemplary liquid pressurizeris a pump.

Some versions of the invention comprise a jet pump, wherein the jet pumpserves as both a liquid pressurizer and a heat-transfer apparatus.

A preferred apparatus includes a first fluid loop and a second fluidloop wherein the apparatus is configured to cycle fluid through thefirst fluid loop and at least intermittently cycle fluid simultaneouslythrough the second fluid loop. The first fluid loop preferably includesthe chamber, the phase separator, the liquid pressurizer, and the vapormixer. The second fluid loop preferably includes the phase separator,the compressor, the condenser, the expansion valve, and the return line.The second fluid loop is configured at least to provide heat to thefirst fluid loop to prepare coolant substantially at saturation.

Another aspect of the invention comprises a method of cooling a surface.A preferred method comprises preparing a coolant approximately atsaturation, wherein the preparing comprises heating pre-heated coolantto approximately a saturation temperature to generate heated coolant.The method also comprises introducing the heated coolant through aninlet of the chamber which includes projecting a stream of the heatedcoolant against the surface, wherein the heated coolant at leastpartially evaporates as it enters the chamber prior to contacting thesurface. The method also comprises draining partially evaporated coolantthrough an outlet of the chamber.

Some versions of the invention include detecting the amount of vaporphase in the heated coolant and regulating the heating in response tothe amount of detected vapor phase.

In some versions of the invention, heating the pre-heated coolantcomprises collecting the partially evaporated coolant draining from theoutlet of the chamber to obtain collected coolant, separating thecollected coolant into liquid coolant and vapor coolant, selectivelypressurizing the liquid coolant to obtain pressurized liquid coolant,and heating the pressurized liquid coolant.

In some versions of the invention, heating the pre-heated coolantcomprises mixing the pre-heated coolant with vapor. One specific versionincludes collecting vapor-containing coolant to obtain collectedcoolant, separating the collected coolant into liquid coolant and vaporcoolant, selectively compressing the vapor coolant to obtain compressedvapor coolant, and mixing at least a first portion of the compressedvapor coolant with the pre-heated coolant. Such a version may furtherinclude condensing at least a second portion of the compressed vaporcoolant to generate condensed coolant, expanding the condensed coolantto approximately a saturation pressure of the condensed coolant togenerate expanded coolant, and directly recycling at least a firstportion of the expanded coolant to be collected and separated and/ormixing at least a second portion of the expanded coolant with the heatedcoolant prior to the introducing the heated coolant through the inlet ofthe chamber.

The system described herein minimizes circulating oil through thechamber by providing circulation routes that bypass the chamber, adjuststo warm or varying sink temperatures by providing for decoupling fromthe temperature sink (i.e., the ambient), and provides redundant coolingmechanisms.

The objects and advantages of the invention will appear more fully fromthe following detailed description of the preferred embodiment of theinvention made in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic of an apparatus of the present invention forcooling a work piece surface.

FIG. 2 depicts a side elevation cutaway view a chamber of the presentinvention comprising tubular nozzles directed non-perpendicularly at thesurface and projecting a stream non-perpendicularly against the surface.

FIG. 3 depicts a top cutaway view of a portion of an array of tubularnozzles as taken from line 3 in FIG. 2.

FIG. 4 depicts a top plan view of a surface upon which an array ofstreams impinges non-perpendicularly.

FIG. 5A depicts a cutaway view of one version of a vapor mixer.

FIG. 5B depicts a cutaway view of another version of a vapor mixer.

FIG. 6 depicts a jet pump, which may be used as both a liquidpressurizer and a vapor mixer in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

One aspect of the present invention involves cooling a surface in achamber with a liquid coolant wherein the coolant at least partiallyundergoes a phase change to a vapor (i.e., evaporates) upon entering thechamber and prior to contacting the surface. This is achieved bypreparing coolant to be introduced in the chamber at or approximately atthe coolant's saturation condition.

The general term “coolant” refers to any fluid capable of undergoing aphase change from liquid to vapor or vice versa at or near the operatingtemperatures and pressures of an apparatus as described herein. The termrefers herein to the fluid in the liquid phase, the vapor phase, andmixtures thereof. A number of coolants may be selected for use withinthe apparatus described herein depending on cost and level ofoptimization desired. Non-limiting examples include water, HFE-7000,R-245fa, FC-72, and FC-40. Other coolants are known in the art. Water isreadily abundant and inexpensive. However, it does not change phase at alow temperature (such as 40° C. or 50° C.) without operating at very lowpressures that can be difficult to maintain. In addition, water as acoolant requires a number of additives and absorbs a range of materialsfrom the surfaces with which it comes into contact. During phase change,these materials may come out of solution, causing fouling or otherissues. Therefore, it is preferred that a pure dielectric fluid, such asHFE-7000 or R-245fa, is used as a coolant. Such coolants are preferablyused in direct contact with the processor package or surface. Thiseliminates the requirement for thermal interference materials betweenthe coolant and the work piece to be cooled and thereby eliminates theirassociated resistances.

“Preparing,” used with reference to preparing coolant at or slightlybelow saturation, refers to any physical manipulation that renders acoolant at its saturation condition. Non-limiting examples of suchphysical manipulations include expanding (i.e., de-pressurizing) and/orheating a coolant.

“Saturation” or “saturation condition,” used with respect to a coolantat saturation or at its saturation condition, respectively, refers to atemperature and pressure at which a liquid is in equilibrium with itsvapor phase. “Saturation temperature” refers to a particular temperatureat a given pressure at which a liquid is in equilibrium with its vaporphase. “Saturation pressure” refers to a particular pressure at a giventemperature at which a liquid is in equilibrium with its vapor phase. Aliquid at saturation evaporates into its vapor phase as additionalthermal energy (heat) is applied or as pressure is reduced. Similarly, avapor at saturation condenses into its liquid phase as thermal energy isremoved or as pressure is increased. The saturation temperature can beincreased by increasing the pressure in the system. Conversely, thesaturation temperature can be lowered by decreasing the pressure in thesystem. The saturation pressure can be increased by increasing thetemperature in the system. Conversely, the saturation pressure can belowered by decreasing the temperature in the system. Establishing atemperature of coolant to be introduced in a chamber at or approximatelyat the saturation condition of the coolant provides for at least aportion of the coolant entering the chamber to evaporate as a result ofundergoing a pressure drop upon entering the chamber, with the coolantfurther evaporating upon being heated by the surface.

In specific versions of the invention, a coolant “approximately at” thecoolant's saturation condition refers to the coolant being slightlybelow the coolant's saturation temperature and slightly above thecoolant's saturation pressure. “Slightly below the coolant's saturationtemperature” refers to a temperature about 0.5° C., about 1° C., about3° C., about 5° C., about 7° C., about 10° C., about 15° C., or about20° C. below the saturation temperature. “Slightly above the coolant'ssaturation pressure” refers to a pressure about 1 kPa, about 3 kPa,about 5 kPa, about 7 kPa, about 10 kPa, about 15 kPa, or about 20 kPaabove the saturation pressure.

“Fluid communication” between two or more elements refers to aconfiguration in which fluid can be communicated between or among theelements and does not preclude the possibility of having a filter, flowmeter, a closable valve, or other devices disposed between suchelements.

“Regulated fluid communication” between two or more elements refers tofluid communication between or among the elements that can be increased,decreased, and/or closed, such as with an adjustable valve.

“Liquid source” refers to any source of a liquid, such as liquidcoolant, without limitation. The liquid source preferably includes aphase separator that collects cycling coolant in a closed fluidic systemand separates liquid from vapor, as described below. However, the liquidsource may also comprise a liquid reservoir in an open fluidic system,wherein coolant is not cycled through the system.

“Vapor source” refers to any source of vapor, such as vapor coolant,without limitation. The vapor source preferably includes a phaseseparator that collects cycling coolant in a closed fluidic system andseparates liquid from vapor, as described below. However, the vaporsource may also comprise a vapor tank or reservoir in an open fluidicsystem wherein coolant is not cycled through the system.

“Heat-transfer apparatus” refers to any device capable of transferringheat to liquid coolant. Suitable heat-transfer apparatuses for use inthe present invention include, without limitation, vapor mixers,condensers, heat exchangers, and jet pumps.

“Heat-transfer regulator” refers to any device capable of adjusting, orcausing to adjust, an amount of heat transferred via the heat-transferapparatus to a liquid. Suitable heat-transfer regulators may include,without limitation, any or all of a vapor valve, a two-phase flowdetector, and/or a processor in communication with the vapor valve andthe two-phase flow detector.

“Downstream” and “upstream” are used herein in relation to the directionof flow of coolant within the apparatus. As is known in the art, fluidflows from areas of higher pressure to areas of lower pressure.

“Selectively,” used in reference to selectively performing an action onor with liquid, refers to performing that action on or with liquidsubstantially devoid of vapor. “Selectively” used in reference toselectively performing an action on or with vapor refers to performingthat action on or with vapor substantially devoid of liquid.

“Pressurizing” a substance refers to increasing the pressure of asubstance. “De-pressurizing” refers to decreasing the pressure of asubstance.

“Operationally connected” refers to a configuration in which one devicemonitors, regulates, or controls the operation or functioning of anotherdevice or is in communication with another device.

An exemplary apparatus 1 of the present invention is shown in FIG. 1.The apparatus 1 comprises two fluid loops, a liquid-evaporation loop 30and a vapor-compression loop 20. The liquid-evaporation loop 30 includesa chamber 11, a phase separator 12, a liquid pressurizer 31, a vapormixer 32, a distal portion of the inlet feed line 34, and a proximalportion of the inlet feed line 13, all in fluid communication. Theliquid-evaporation loop 30 also includes a two-phase flow detector 33operationally connected with the distal portion of the inlet feed line34 and disposed downstream of the vapor mixer 32. The vapor-compressionloop 20 includes the phase separator 12, a compressor 21, a condenser22, an expansion valve 23, and a return line 25, all in fluidcommunication.

The phase separator 12 serves as the only point of mutual convergencebetween the vapor-compression loop 20 and the liquid-evaporation loop30. Here, the phase separator 12 accepts coolant draining from thechamber of the liquid-evaporation loop 30 as well as coolant recyclingfrom the return line 25 of the vapor-compression loop 20. The phaseseparator 12 also serves as the only point of mutual divergence, whereinaccumulated coolant is separated within the phase separator 12 intovapor coolant and liquid coolant. The vapor coolant is selectivelydiverted to the compressor 21 of the vapor-compression loop 20. Theliquid coolant is selectively diverted to the liquid pressurizer 31 ofthe liquid-evaporation loop 30.

The vapor mixer 32 of the liquid-evaporation loop 30 serves as one oftwo points where the vapor-compression loop 20 feeds into theliquid-evaporation loop 30. The vapor-compression loop 20unidirectionally feeds into the vapor mixer 32 in a regulated mannerthrough the vapor-mixer feed line 14. In this manner, hot vapor coolantfrom the compressor 21 mixes with liquid coolant from the liquidpressurizer 31 in the vapor mixer 32, thereby heating the liquid. It ispreferred that the hot vapor coolant heats the liquid coolant to itssaturation temperature. The degree to which the liquid is heated is afunction, in part, of the amount of hot vapor diverted from thevapor-compression loop 20 into the vapor mixer 32 and the amount ofthermal energy contained by the vapor. The amount of vapor coolantdiverted from the vapor-compression loop 20 into the vapor mixer 32 isregulated by a vapor valve 15. The vapor valve 15 can continuously openor close to allow more or less vapor, respectively, to flow into thevapor mixer 32, or can completely close.

The vapor valve 15 itself is further regulated by the two-phase flowdetector 33, the latter of which is in configured in communication 331with the vapor valve 15. The two-phase flow detector 33 detects whetheror not two-phases (i.e., liquid and vapor bubbles) are present withinthe coolant in the distal portion of the inlet feed line 34, therebyindicating whether or not the coolant heated by the vapor coolant is atsaturation. If bubbles are not detected, the two-phase flow detector 33can communicate with the vapor valve 15 to progressively open and allowmore vapor to mix with the liquid coolant until bubbles are detected.The two-phase flow detector 33 also preferably detects the amount orconcentration of bubbles within the coolant in the distal portion of theinlet feed line 34, thereby determining the amount of vapor within theliquid. The two-phase flow detector 33 can then communicate with thevapor valve 15 to either open or close in a continuous manner until apre-defined level of evaporation is achieved. If there is too much vapordetected by the two-phase flow detector 33, the two-phase flow detector33 communicates with the vapor valve 15 to close in a continuous manneruntil the pre-defined level of vapor is achieved. If there is too littlevapor, the two-phase flow detector 33 communicates with the vapor valve15 to open in a continuous manner until the pre-defined level ofevaporation is achieved. Various exemplary pre-defined levels ofevaporation include about 1% vapor, about 2.5% vapor, about 5% vapor,about 7.5% vapor, about 10% vapor, about 15% vapor, about 20% vapor ormore. The vapor valve 15 preferably includes a manual override function,wherein an operator can manually open or close the valve independentlyof the other components of the apparatus 1. The vapor valve 15 can alsobe completely closed to permit cooling with only the liquid-evaporationloop 30 in certain desired circumstances.

The proximal portion of the inlet feed line 13 serves as the second ofthe two points where the vapor-compression loop 20 feeds into theliquid-evaporation loop 30 in a regulated manner. Here, thevapor-compression loop 20 at a point downstream of the expansion valve23 feeds into the liquid-evaporation loop 30 at a point downstream ofthe two-phase flow detector 33. A circuit valve 24 regulates the amountof condensed, expanded coolant from the vapor-compression loop 20 thatmerges with the liquid-evaporation loop 30. The circuit valve 24 iscapable of completely closing to permit cooling with theliquid-evaporation loop 30 only, if desired, but is otherwisecontinuously adjustable. The circuit valve 24 is preferablyindependently adjustable with respect to other components of theapparatus 1. Allowing condensed, expanded coolant from thevapor-compression loop 20 to merge with the liquid-evaporation loop 30by opening or otherwise adjusting the circuit valve 24 helps to regulatethe pressure in the chamber 11. The portion of the condensed, expandedcoolant that is not merged to the proximal portion of the inlet feedline 13 is recycled to the phase separator 12 via the return line 25.

An exemplary version of a chamber 11 is shown in FIG. 2. The chamber 11includes a surface 111 to be cooled exposed therein, one or more inlets113 to permit fluid to enter the chamber 11, and one or more outlets 114to permit fluid to exit the chamber 11. In this manner, the chamber 11is configured to permit fluid to flow therethrough. The inlets 113 arepreferably configured to project a stream 115 of a fluid, such as acoolant, against the surface 111. The stream 115 of fluid projectedagainst the surface 111 is preferably a spray stream but may also be ajet stream. As used herein, a “spray” or “spray stream” refers to asubstantially atomized liquid fluid projected through a vapor medium.“Spray” or “spray stream” is contrasted with “jet” or “jet stream,”wherein “jet” or “jet stream” refers to a substantially liquid fluidfilament that is projected through a substantially liquid or vapormedium or mixture thereof.

The surface 111 exposed within the chamber 11 preferably comprises asurface portion of a work piece 112, such that the streams 115 ofcoolant impinge directly on the work piece 112 without thermalinterference materials disposed between the work piece 112 and thecoolant. As used herein, “work piece” refers to any electronic ornon-electronic device having a surface that generates heat and that isdesired to be cooled. Non-limiting, exemplary work pieces 112 includemicroprocessors, microelectronic circuit chips in supercomputers, or anyother electronic circuits or devices requiring cooling such as diodelaser packages. The surface 111 can be exposed within the chamber 11 byconstructing the chamber 11 around the work piece 112 to include thesurface 111 within the chamber 11. Thus, the work piece 112 or thesurface 111 thereof constitutes one wall of the chamber 11.

The one or more inlets 113 of the chamber 11 may comprise any inletsknown in the art, including any slits, apertures, or nozzles suitablefor generating a stream 115 of coolant against a surface 111. See, e.g.,U.S. Pat. Pub. 2006/0196627 to Shedd et al. and U.S. Pat. No. 6,993,926to Rini et al. Various types of nozzles include pressure atomizernozzles, vapor assist nozzles, and vapor atomizer nozzles. The inlets113 may comprise apertures in a generally flat nozzle plate butpreferably comprise one or more tubular nozzles 131 that extend into thechamber 11. The tubular nozzles 131 provide a drainage path 132 forvapor or liquid coolant through the chamber 11. The drainage path 132provided by the tubular nozzles 132 prevents exiting coolant fromsubstantially interfering with the streams 115 projected from the inlet113 and thereby substantially protect the incoming streams 115 from theexiting, warm coolant. The tubular nozzles 131 and optional associatedinlet manifold 134 may be made from a variety of materials selected forease of manufacture and compatibility with the chosen coolant. They mayeven be injection molded to cut manufacturing costs significantly.

Each tubular nozzle 131 comprises a central axis 133 defined by theextended dimension of the tubular nozzle 131. The central axis 133 ofthe tubular nozzle 131 may either be angled perpendicularly with respectto the surface 111 or angled non-perpendicularly with respect to thesurface 111, the latter of which is shown in FIG. 2. If anglednon-perpendicularly with respect to the surface 111, the central axis133 may define any angle between 0° and 90° with respect to the surface111, such as about 5°, about 10°, about 15°, about 20°, about 25°, about30°, about 35°, about 40°, about 45°, about 50°, about 55°, about 60°,about 65°, about 70°, about 75°, about 80° or about 85° or any rangetherebetween. The tubular nozzles 131 may comprise any cross-sectionalshape when viewed along the central axis 133. Various versions include acircular shape, an oval shape (to generate a fin-shaped nozzle), andvirtually any other cross-sectional shape.

The chamber 11 preferably includes an array 135 of tubular nozzles 131.The central axes 133 of the tubular nozzles 131 in the array 135 maydefine different angles with respect to the surface 111. A preferredarrangement is wherein the central axis 133 of each tubular nozzle 131in the array 135 comprises the same angle with respect to surface 111,as shown in FIG. 2.

The array of tubular nozzles 131 may be arranged in any configurationsuitable for cooling the surface 111. In a version of the inventiondepicted in FIG. 3, the arrays 135 are organized into staggered columns136 and rows 137. The staggering of tubular nozzles 131 in the array 135is such that a given tubular nozzle 131 in a given column 136 and row137 does not have a corresponding tubular nozzle 131 in a neighboringrow 137 in the given column 136 or a corresponding tubular nozzle 131 ina neighboring column 136 in the given row 137. If the tubular nozzles131 are configured to induce a substantially same direction of flow 145along the surface 111 (see below), either the columns 136 or the rows137 are preferably oriented substantially perpendicularly to thesubstantially same direction of flow 145. Arrays 135 of tubular nozzles131 in a non-staggered arrangement can also be used in the presentinvention.

The tubular nozzle 131 may be configured to project a stream 115 havingany of a variety of shapes and any of a variety of trajectories. Withregard to shape, the stream 115 is preferably a symmetrical stream. Asused herein, “symmetrical stream,” refers to a stream 115 that issymmetrical in cross section. Examples of symmetrical streams includelinear streams, fan-shaped streams, and conical streams. Linear streamshave a substantially constant cross section along their length. Conicalstreams have a round cross section that increases along their length.Fan-shaped streams have a cross section along their length with onecross-sectional axis being significantly longer than a second,perpendicular cross-sectional axis. In some versions of the conicalstreams, at least one and possibly both of the cross-sectional axesincrease in length along the length of the stream. With regard totrajectory, the stream 115 preferably comprises a central axis 116 (seeFIG. 2). For the purposes herein, the “central axis 116 of the stream115” is the line formed by center points of a series of transverseplanes taken along the length of the stream 115, wherein each transverseplane is oriented to overlap with the smallest possible surface area ofthe stream 115, and each center point is the point on the transverseplane that is equidistant from opposing edges of the stream 115 alongthe transverse plane. In preferred versions, the tubular nozzle 131projects a stream 115 having a central axis 116 that is substantiallycollinear with the central axis 133 of the tubular nozzle 131. However,the tubular nozzle 131 may also project a stream 115 having a centralaxis 116 that is angled with respect to the central axis 133 of thetubular nozzle 131. The angle of the central axis 116 of the stream 115with respect to the central axis 133 of the tubular nozzle 131 may beany angle between 0° and 90°, such as about 1°, about 2°, about 3°,about 4°, about 5°, about 7°, about 10°, about 15°, about 20°, about25°, about 30°, about 35°, about 40°, about 45°, about 50°, about 55°,about 60°, about 65°, about 70°, about 75°, or about 80° or any rangetherebetween. In such versions, the tubular nozzle 131 preferablyprojects a stream 115 wherein at least one portion of the stream 115 isprojected along the central axis 133 of the tubular nozzle 1310.However, the tubular nozzle 131 may also project a stream 115 wherein noportions of the stream 115 are projected along the central axis 133 ofthe tubular nozzles 131.

Similarly, the tubular nozzle 131 may be configured to project a stream115 that impinges on the surface 111 at any of a variety of angles. Insome versions, the tubular nozzle 131 projects a stream 115 at thesurface 111 such that the entire stream (in the case of a linearstream), or at least the central axis 116 of the stream 115 (in the caseof conical or fan-shaped streams), impinges perpendicularly on thesurface 111 (i.e., at a 90° angle with respect to the surface).Perpendicular impingement upon a surface 111 induces radial flow ofcoolant 144 from contact points 141 along the surface 111. While arrays140 of perpendicularly impinging streams 115 are suitable for someapplications, they are not optimal in efficiency. This is becauseopposing coolant flow from neighboring contact points interacts to formstagnant regions. Heat transfer performance in these stagnant regionscan fall to nearly zero.

In a preferred version of the invention, the tubular nozzles 131 areconfigured to project a stream 115 that impinges on the surface 111 suchthat at least the central axis 116 of the stream 115, and morepreferably the entire stream 115, impinges non-perpendicularly on thesurface 111 (i.e, at an angle other than 90° with respect to thesurface). As a non-limiting example, the central axis 116 of the stream115 may impinge on the surface 111 at any angle between 0° and 90°, suchas about 1°, about 2°, about 3°, about 4°, about 5°, about 7°, about10°, about 15°, about 20°, about 25°, about 30°, about 35°, about 40°,about 45°, about 50°, about 55°, about 60°, about 65°, about 70°, about75°, or about 80° or any range therebetween. FIG. 4 depicts a top planview of a surface 111 on which each stream 115 of an array of streamsimpinges non-perpendicularly on the surface 111. Such impingementcreates a flow pattern in which all the coolant 144 flows along thesurface 111 in the substantially same direction 145. In some versions ofpatterns flowing in the substantially same direction 145, flow ofcoolant 144 at each portion of the surface 111 comprises a commondirectional vector component along a plane defined by the surface 111.In other versions, coolant 144 at no two points on the surface 111 flowsin opposite directions. In yet other versions, coolant 144 at no twopoints on the surface 111 flows in opposite directions or flows inperpendicular directions. Flowing coolant 144 in the substantially samedirection eliminates stagnant regions on the surface 111.

As further shown in FIG. 4, tubular nozzles 131 in an array 140 arepreferably configured to impinge streams 115 on the surface 111 in anarray 140 of contact points 141 comprising staggered columns 142 androws 143. The staggering is such that a given contact point 141 in agiven column 142 and row 143 does not have a corresponding contact point141 in a neighboring column 142 in the given row 143 or a correspondingcontact point 141 in a neighboring row 143 in the given column 142. Ifthe coolant 144 is induced to flow across the surface 111 in asubstantially same direction 145, as in FIG. 4, either the columns 142or the rows 143 are preferably oriented substantially perpendicularly tothe substantially same direction 145 of flow. Arrays 140 of contactpoints 141 arranged in this manner permit coolant 144 emanating fromeach contact point 141 in a given column 142 or row 143 to flowsubstantially between contact points 141 in a neighboring column 142 orrow 143, respectively, as shown in FIG. 4. Even, consistent flow ofcoolant 144 over a surface 111 without stagnant regions as provided bythis configuration encourages bubble generation and evaporation ofcoolant 144 contacting the surface 111 whereby the heat transferperformance increases significantly.

The phase separator 12, or vapor-liquid separator, includes any devicecapable of separating the vapor and liquid phases of coolant exitingfrom the chamber 11 and selectively distributing each separated phase toa downstream device. The phase separator 12 is preferably also capableof collecting, accumulating, and storing coolant when not cyclingthrough the device. The phase separator 12 in this respect also servesas a volume buffer, which is useful in accommodating varying heat loads.A preferred phase separator 12 is an accumulator, many versions of whichare known in the art. In one version, an accumulator is a verticalvessel comprising one or more inlets 121, a vapor outlet 122 on an upperportion of the vessel and a liquid outlet 123 near a lower portion ofthe vessel (see FIG. 1). Mixed-phase fluid enters the inlet 121 orinlets 121. The liquid portion of the mixed-phase fluid settles to thebottom of the vessel by gravity, wherein it is withdrawn through theliquid outlet 123. The vapor travels upward, preferably at a designvelocity which minimizes entrainment of liquid droplets as the vaporexits through the vapor outlet 122. Phase separators are also known inthe art as flash drums, knock-out drums, knock-out pots, compressorsuction drums, accumulators, receivers or compressor inlet drums.

The compressor 21 includes any device capable of compressing, orpressurizing, a vapor. Common suitable compressors includereciprocating, rotary screw, scroll, centrifugal, diaphragm, axial-flow,diagonal or mixed-flow, liquid-ring, or roots blower compressors.Reciprocating compressors are piston-style, positive displacementcompressors. Rotary screw compressors are also positive displacementcompressors, but employ two meshing screw-rotors that rotate in oppositedirections to trap vapor and reduce the volume of the vapor along therotors to a discharge point. Scroll compressors are also positivedisplacement compressors, wherein vapor is compressed when one spiralorbits around a second stationary spiral, thereby creating smaller andsmaller pockets and higher pressures. Centrifugal compressors aredynamic compressors that raise the pressure of the vapor by impartingvelocity to a vapor, typically using a rotating impeller, and convertingthe velocity to pressure. Diaphragm, axial-flow, diagonal or mixed-flow,liquid-ring, and roots blower compressors are well-known in the art andare not described in detail herein. The compressor 21 can be open,hermetic, or semi-hermetic, with respect to how the compressor and/ormotor is situated in relation to the refrigerant being compressed.Typically in hermetic, and most semi-hermetic compressors (sometimesknown as accessible hermetic compressors), the compressor and motordriving the compressor are integrated and operate within the coolantsystem. The motor is hermetic and is designed to operate, and be cooledby, the coolant being compressed. An open compressor has a motor drivewhich is outside of the coolant system, and provides drive to thecompressor by means of an input shaft with suitable gland seals. Opencompressor motors are typically air cooled.

The condenser 22 includes any device capable of cooling and condensingthe compressed vapor into a liquid form. The condenser 22 may thereforeinclude any heat exchanger known in the art. Suitable heat exchangersmay exchange heat from the compressed vapor exiting the compressor to anexternal cooling fluid and/or air. Non-limiting examples includeshell-and-tube, fin-and-tube, micro-channel, plate, adiabatic-wheel,plate-fin, pillow-plate, fluid, dynamic-scraped-surface, phase-change,direct-contact, and spiral heat exchangers. The heat exchanger mayoperate by parallel flow or counter flow.

The expansion valve 23 is preferably configured to expand in a mannerthat forces a drop in pressure of the cooled, condensed liquid coolantto induce evaporation of the coolant. The expansion valve 23 ensuresthat coolant being recycled to the phase separator 12 includes at leasta minimal amount of vapor, the latter of which is separated in the phaseseparator 12 and diverted from the vapor-compression loop 20 to thevapor mixer 32, if required. The expansion valve 23 also ensures thatcoolant diverted from the vapor-compression loop 20 to the chamber 11 isin a saturated condition. The expansion valve 23 is preferablyconfigured to induce the compressed liquid to evaporate to about 1%vapor, about 2.5% vapor, about 5% vapor, about 7.5% vapor, about 10%vapor, about 15% vapor, about 20% vapor or more. Expansion of thecoolant in the expansion valve 23 is accompanied by a drop intemperature.

The liquid pressurizer 31 includes any device capable of pressurizingliquid coolant to a level sufficient to force the coolant through theinlets 113 and against the surface 111. The liquid pressurizer 31 ispreferably a pump. Suitable pumps include gear pumps, variable speedpositive displacement pumps, peristaltic pumps, centrifugal pumpscoupled with a back pressure regulator, or any other pump known in theart. An example of a suitable pump includes the “MICROPUMP”-brand gearpump (Cole-Parmer, Vernon Hills, Ill.). A variable liquid pressurizer,such as a variable speed pump, enables the flow of coolant to be set ata rate required to meet the expected heat load at the surface 111. Theliquid pressurizer 31 may further include a controller with a variablespeed drive. See, e.g., U.S. Pat. Pub. 2006/0196627 to Shedd et al.,incorporated herein by reference. These elements enable the liquidpressurizer 31 to operate at a lower power when the thermal load falls.In place of or in addition to a pump, the liquid pressurizer 31 maycomprise a reservoir of pressurized coolant. Alternatively, the liquidpressurizer 31 may comprise a jet pump, as described in more detailbelow.

The vapor mixer 32 includes any device capable of mixing vapor withliquid coolant. The vapor mixer 32 preferably introduces heat to liquidand thereby increases the enthalpy of the liquid coolant at asubstantially constant pressure. Various exemplary versions are shown inFIGS. 5A-B. In FIG. 5A, a vapor fluid line 321 carrying pressurized, hotvapor, such as that generated by a compressor 21, terminates in aperforated diffuser 323. The perforated diffuser 323 is disposed withina liquid fluid line 322 carrying pressurized liquid, such as thatgenerated by a liquid pressurizer 31, and diffuses the hot vaportherein. In this version, a vapor valve 15 upstream of the diffuser 323may be replaced with a plunger in the perforated diffuser to regulatethe amount of vapor delivered to the liquid. In FIG. 5B, an array oftubes 324 is disposed within a vapor fluid line 321 carrying pressurizedhot vapor in a configuration that permits the vapor to enter a first end325 of the array 324 and exit a second end 326 of the array 324. Aliquid fluid line 322 carrying pressurized liquid terminates in thetubes at perforations in the walls of the tubes. The liquid enters thetubes through the perforations and mixes with the vapor passing through.

In some versions of the invention, the liquid pressurizer 31 and vapormixer 32 can be replaced with a single device that fulfills both thepressurizing and mixing functions, such as a jet pump 40. A suitableexemplary jet pump is shown in FIG. 6. The jet pump 40 uses the Venturieffect of a converging-diverging nozzle to convert the pressure energyof compressed vapor 41 entering the jet pump 40 to a velocity energywithin the jet pump 40. The velocity energy creates a low-pressure zone43 within the jet pump 40 that draws in and entrains liquid coolant 42.The liquid coolant 42 and the vapor 41 mix, pass through a converging“throat” section 44, and subsequently pass through a diverging section45, wherein the velocity energy is converted back to pressure energy.Use of a jet pump 40 permits simultaneous pressurizing and mixing offluid and vapor and can therefore serve both the liquid pressurizing andvapor mixing functions in the apparatus 1. Jet pumps are otherwise knownin the art as an injector, ejector, steam injector, steam ejector,eductor-jet pump, or thermocompressor.

The two-phase flow detector 33, non-limiting examples of which are shownin FIGS. 5A and 5B, includes any device capable of detecting presence,absence, and/or amount of bubbles 332 in a fluid line or tubing. Thetwo-phase flow detector 33 is preferably capable of monitoring fluid inreal-time. The two-phase flow detector 33 preferably runs to a processor(not shown) that determines whether or not there are bubbles 332 inliquid coolant or the degree of bubbles 332 in the liquid coolant. Thepresence of small bubbles 332 indicates that the liquid coolant is atsaturation (no more vapor will condense). The processor then sends acontrol signal to the vapor valve 15 to adjust accordingly. Examples ofsuitable two-phase flow detectors include optical bubble detectors suchas a digital camera 333. The digital camera 333 may be coupled with anLED strobe 334 to provide light for capturing images. Other exemplarybubble detectors include “LIQUID-EYE”-brand (Ivek Corporation, NorthSpringfield, Vt.) and “LIFEGUARD”-brand (Moog, Inc., Salt Lake City,Nev.) bubble detectors. Non-optical detectors include an orifice platewith a pressure sensor to measure increased pressure loss due tobubbles, a fiber optic whose light-carrying properties change when incontact with the vapor of a bubble, or a temperature/pressure sensorcombination that determines when the temperature no-longer changesindependently from the pressure.

Additional chambers 11 may be added to the apparatus 1. The additionalchambers 11 are preferably, but not necessarily, added in parallel suchthat they are serviced by the same vapor-compression loops 20 andliquid-evaporation loops 30. Alternatively or in addition, the apparatus1 may include additional liquid pressurizers 31, compressors 21,condensers 22, two-phase flow detectors 33, vapor mixers 32, etc., inparallel for the purpose of redundancy, reliability, or enhanced coolingeffectiveness. As used herein, an additional component “in parallel”refers to a component in fluid communication with the other componentsin a manner that bypasses only components of the same type withoutbypassing different types of components. For example, an additionalchamber 11 may be added to the apparatus 1 as shown in FIG. 1 by havingthe proximal portion of the inlet feed line 13 split downstream fromwhere the vapor-compression loop 20 merges with it, such that the splitportion of the inlet feed line 13 feeds into two separate chambers 11.Fluid lines in fluid communication with the outlets 114 of the chambers11 would then either converge before feeding into the phase separator 12or would both separately feed into the phase separator 12.

In a variation of the exemplary apparatus 1 described herein, thepressurized liquid may be heated by an alternative heat-transferapparatus, such as one comprising a heat exchanger. The heat exchangermay comprise the heat exchanger of the vapor-compression loop 20 or becoupled thereto, wherein at least some of the heat removed from thecompressed vapor during the condensing step is transferred to the liquidcoolant to generate saturated liquid coolant. The heat exchanger ispreferably configured to vary the amount of heat transferred inaccordance with a signal sent from the two-phase flow detector 33 or aprocessor operationally connected thereto.

In another variation of the exemplary apparatus 1 described herein, theliquid loop 30 also includes a circuit valve, which enables thevapor-compression loop 20 to cool the chamber 11 in the manner of aconventional vapor-compression cooling system without the aid of theliquid-evaporation loop 30.

In yet another variation of the exemplary apparatus 1 described herein,the expansion valve 23 may be adjustable to vary the degree ofexpansion. In addition, a second two-phase flow detector 33 may bedisposed downstream of the adjustable expansion valve 23 to regulate thedegree of evaporation in expanded coolant, thereby providing anadditional control to ensure that coolant entering the phase separator12 or the chamber 11 is at saturation.

An exemplary method of cooling a surface 111 includes collecting in aphase separator 12, such as an accumulator, coolant draining from anoutlet 114 of the chamber 11. The phase separator 12 separates collectedvapor coolant from collected liquid coolant. The phase separator 12 thendelivers the separated vapor coolant to the compressor 21 forcirculation in a vapor-compression loop 20 and delivers the separatedliquid coolant to the liquid pressurizer 31 for circulation in aliquid-evaporation loop 30.

In the vapor-compression loop 20 the compressor 21 compresses theseparated vapor coolant and simultaneously increases its temperature aswell. An amount of the heated, compressed vapor is diverted to the vapormixer 32 of the liquid-evaporation loop as needed to ensure two-phaseflow in the liquid-evaporation loop. The remaining heated, compressedvapor proceeds to the condenser 22, where it is cooled and condensedinto a liquid. The cooled and condensed liquid proceeds through theexpansion valve 23, wherein it undergoes an abrupt reduction inpressure, resulting in evaporation of the liquid and a further reductionin temperature. The coolant at this point is at its saturation state.Depending on the degree at which the circuit valve 24 is opened, acertain proportion (0-100%) of the saturated coolant is diverted to theliquid-evaporation loop 30 through the proximal portion of the inletfeed line 13 and the chamber 11 before being recycled back to the phaseseparator 12. This diverted saturated coolant is used to regulate thepressure in the chamber 11. The diverted saturated coolant also aids theliquid-evaporation loop 30 in cooling the surface 111 in the manner of aconventional refrigeration cycle. The degree to which the circuit valve24 is opened or closed is preferably a function of the pressure requiredfor cooling the surface 111 in the chamber 11. The remaining proportion(0-100%) of the saturated coolant is directly recycled back to the phaseseparator 12 via the return line 25. The recycled saturated coolantensures that a certain degree of vapor is supplied to the phaseseparator 12 for downstream use.

In the liquid-evaporation loop 30, the liquid pressurizer 31 pressurizesthe separated liquid coolant. The pressurized liquid coolant is thenheated. The pressurized liquid coolant is preferably heated by mixingwith the hot, compressed vapor emerging from the compressor 21 in thevapor mixer 32, wherein the vapor is diverted to the vapor mixer 32 byvirtue of the vapor valve 15 being open. The heated coolant then passesthe two-phase flow detector 33. If the heated coolant does not containbubbles 332, the two-phase flow detector 33 communicates to the vaporvalve 15, such as through a processor, to progressively open andincrease the amount of vapor passing into the vapor mixer 32 to increaseheating of the liquid coolant. If the heated coolant contains too manybubbles 332, the two-phase flow detector 33 communicates to the vaporvalve 15 to progressively close to reduce the amount of vapor passinginto the vapor mixer 32 to decrease heating of the liquid coolant. Inthis manner, the two-phase flow detector 33 and vapor valve 15 regulatethe heating of the liquid coolant. The detection of bubbles 332 ensuresthat the liquid coolant is heated to its saturation temperature prior toentering the chamber 11. After being heated to its saturationtemperature, the heated coolant is either injected directly into thechamber 11 or mixed with the saturated coolant from thevapor-compression loop 20 before being injected into the chamber 11.

The coolant is introduced in the chamber 11 and projected against thesurface 111 either as a spray stream or as a jet stream. It is preferredthat the coolant being introduced is at or approximately at saturationsuch that it at least partially evaporates upon entering the chamber 11.The evaporation is induced by the pressure drop that the coolantundergoes upon passing into the chamber 11 from the inlets 113. Theevaporation is particularly preferred for spray streams, wherein theevaporation aids in atomizing the coolant. The evaporation cools thecoolant prior to contacting the surface 111. Further evaporation of thecoolant upon contacting the surface 111 and subsequently being heated byit results in efficient cooling of the surface 111. The vapor coolantand remaining liquid coolant then drain from the chamber 11 through theoutlet 114 and return to the phase separator 12 for further cycles.

In a preferred version of the invention, the cooling system is designedherein to permit cycling of coolant through the liquid-evaporation loop30 simultaneously and in parallel with the vapor-compression loop 20,wherein the liquid-evaporation loop 30 is primarily responsible forcooling the surface 111, and the vapor-compression loop 20 aids theliquid-evaporation loop 30 by regulating pressure in the chamber 11,maintaining desired conditions in the phase separator 12, and providingheated, compressed vapor to the liquid-evaporation loop 30 to ensuresaturated coolant enters the chamber 11. The vapor-compression loop canalso contribute to providing saturated coolant to the chamber 11 whenand to the degree that the circuit valve 24 is open. With the supportingrole of the vapor-compression loop 20 in this version, it is notnecessary that coolant is constantly cycled through thevapor-compression loop 20. Coolant may instead be cycled through thevapor-compression loop 20 intermittently and only as needed to fulfillits supporting roles.

The present invention is directed, in part, to preparing coolant so thatit evaporates upon entering the chamber 11 and prior to contacting thesurface 111. This is distinct from evaporation that occurs after thecoolant contacts the surface 111 and is heated by it.

The elements and method steps described herein can be used in anycombination whether explicitly described or not. All combinations ofmethod steps as described herein can be performed in any order, unlessotherwise specified or clearly implied to the contrary by the context inwhich the referenced combination is made.

As used herein, the singular forms “a,” “an,” and “the” include pluralreferents unless the content clearly dictates otherwise.

Numerical ranges as used herein are intended to include every number andsubset of numbers contained within that range, whether specificallydisclosed or not. Further, these numerical ranges should be construed asproviding support for a claim directed to any number or subset ofnumbers in that range. For example, a disclosure of from 1 to 10 shouldbe construed as supporting a range of from 2 to 8, from 3 to 7, from 5to 6, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth.

All patents, patent publications, and peer-reviewed publications (i.e.,“references”) cited herein are expressly incorporated by reference tothe same extent as if each individual reference were specifically andindividually indicated as being incorporated by reference. In case ofconflict between the present disclosure and the incorporated references,the present disclosure controls.

The methods and compositions of the present invention can comprise,consist of, or consist essentially of the essential elements andlimitations described herein, as well as any additional or optionalsteps, ingredients, components, or limitations described herein orotherwise useful in the art.

The present disclosure is filed simultaneously with U.S. applicationSer. No. ______ to Timothy A. Shedd, filed Apr. ______, 2011 underAttorney Docket Number 09820.948, and entitled High Efficiency ThermalManagement System, the entirety of which is incorporated herein byreference.

It is understood that the invention is not confined to the particularconstruction and arrangement of parts herein illustrated and described,but embraces such modified forms thereof as come within the scope of theclaims.

1. An apparatus for cooling a surface comprising: at least one chamberwith the surface exposed therein, the chamber comprising an inlet and anoutlet and being configured for flowing fluid therethrough by enteringthrough the inlet in a stream projected against the surface and exitingthrough the outlet; a liquid source in fluid communication with theinlet of the chamber; and a heat-transfer apparatus configured totransfer heat to liquid derived from the liquid source upstream of theinlet.
 2. The apparatus of claim 1 further comprising a heat-transferregulator configured to adjust amount of heat transferred via theheat-transfer apparatus to the liquid.
 3. The apparatus of claim 2wherein the heat-transfer regulator comprises a two-phase flow detectordisposed between the heat-transfer apparatus and the inlet, thetwo-phase flow detector configured to communicate with a device thatadjusts an amount of heat transferred via the heat-transfer apparatus tothe liquid in response to an amount of vapor phase detected in theliquid.
 4. The apparatus of claim 1 wherein the heat-transfer apparatuscomprises a vapor mixer in fluid communication with the liquid sourceand a vapor source.
 5. The apparatus of claim 4 further comprising avapor valve disposed between the vapor mixer and the vapor source, thevapor valve configured to adjust flow of vapor to the vapor mixer. 6.The apparatus of claim 5 further comprising a two-phase flow detector incommunication with the vapor valve and disposed between the vapor mixerand the inlet, the two-phase flow detector configured to communicatewith the vapor valve to adjust flow of vapor to the vapor mixer inresponse to an amount of vapor phase detected in the liquid.
 7. Theapparatus of claim 1 wherein the liquid source comprises: a phaseseparator in fluid communication with the outlet of the chamber; and aliquid pressurizer in fluid communication with the phase separator in aconfiguration to selectively receive liquid therefrom, the liquidpressurizer further being in fluid communication with the heat-transferapparatus.
 8. The apparatus of claim 1 wherein the heat-transferapparatus comprises a vapor mixer in fluid communication with the liquidsource and a vapor source, wherein the vapor source comprises: a phaseseparator; and a compressor in fluid communication with the phaseseparator in a configuration to selectively receive vapor therefrom, thecompressor further being in regulated fluid communication with the vapormixer.
 9. The apparatus of claim 8 further comprising: a condenser influid communication with the compressor in a configuration to receivefluid therefrom and further in fluid communication with the phaseseparator via a return line in a configuration to deliver fluid to thephase separator; and an expansion valve disposed between the condenserand the return line.
 10. The apparatus of claim 9 wherein the condenseris further in fluid communication with the inlet of the chamber todeliver fluid thereto, the chamber is in fluid communication with thephase separator to deliver fluid thereto, and the apparatus furthercomprises: a circuit valve disposed between the expansion valve and theinlet, the circuit valve configured to adjust flow of fluid from theexpansion valve to the inlet.
 11. The apparatus of claim 10 furthercomprising: a first fluid loop comprising: the chamber; a phaseseparator as the liquid source, wherein the phase separator is in fluidcommunication with the outlet of the chamber; a liquid pressurizer influid communication with the phase separator in a configuration toselectively receive liquid therefrom, the liquid pressurizer furtherbeing in fluid communication with the heat-transfer apparatus; and thevapor mixer; and a second fluid loop comprising: the phase separator;the compressor; the condenser; the expansion valve; and the return line,wherein the apparatus is configured to cycle fluid through the firstfluid loop and at least intermittently cycle fluid simultaneouslythrough the second fluid loop.
 12. The apparatus of claim 1 wherein theheat-transfer apparatus comprises a heat exchanger.
 13. The apparatus ofclaim 1 wherein the heat-transfer apparatus comprises a jet pump.
 14. Amethod of cooling a surface within a chamber comprising: preparing acoolant approximately at saturation, wherein the preparing comprisesheating pre-heated coolant to approximately a saturation temperature togenerate heated coolant; introducing the heated coolant through an inletof the chamber which includes projecting a stream of the heated coolantagainst the surface, wherein the heated coolant at least partiallyevaporates as it enters the chamber prior to contacting the surface; anddraining partially evaporated coolant through an outlet of the chamber.15. The method of claim 14 further comprising detecting amount of vaporphase in the heated coolant and regulating the heating in response tothe amount of detected vapor phase.
 16. The method of claim 14 whereinthe heating comprises: collecting the partially evaporated coolantdraining from the outlet of the chamber to obtain collected coolant;separating the collected coolant into liquid coolant and vapor coolant;selectively pressurizing the liquid coolant to obtain pressurized liquidcoolant; and heating the pressurized liquid coolant.
 17. The method ofclaim 14 wherein the heating comprises mixing the pre-heated coolantwith vapor.
 18. The method of claim 17 wherein the heating comprises:collecting vapor-containing coolant to obtain collected coolant;separating the collected coolant into liquid coolant and vapor coolant;selectively compressing the vapor coolant to obtain compressed vaporcoolant; and mixing at least a first portion of the compressed vaporcoolant with the pre-heated coolant.
 19. The method of claim 18 furthercomprising: condensing at least a second portion of the compressed vaporcoolant to generate condensed coolant; expanding the condensed coolantto approximately a saturation pressure of the condensed coolant togenerate expanded coolant; and performing a process selected from thegroup consisting of: recycling at least a first portion of the expandedcoolant, wherein the first portion of the expanded coolant comprises atleast a portion of the vapor-containing coolant in the collecting step;and mixing at least a second portion of the expanded coolant with theheated coolant prior to the introducing the heated coolant through theinlet of the chamber, wherein the collecting the vapor-containingcoolant includes collecting the partially evaporated coolant drainingfrom the outlet of the chamber.
 20. A method of cooling a surface withina chamber comprising cycling fluid through a first loop and at leastintermittently cycling fluid simultaneously through a second loop,wherein: the cycling through a first loop comprises: introducing asubstantially saturated coolant through an inlet of the chamber whichincludes projecting a stream of the substantially saturated coolantagainst the surface, wherein the substantially saturated coolant atleast partially evaporates as it enters the chamber prior to contactingthe surface; draining partially evaporated coolant through an outlet ofthe chamber; collecting the partially evaporated coolant to obtaincollected coolant; separating the collected coolant into liquid coolantand vapor coolant; selectively pressurizing the liquid coolant to obtainpressurized liquid coolant prior to the introducing; and the cyclingthrough the second loop comprises: the collecting, wherein thecollecting further comprises collecting vapor-containing coolant; theseparating; selectively compressing the vapor coolant to obtaincompressed vapor coolant; mixing at least a first portion of thecompressed vapor coolant with the pressurized liquid coolant to generatethe coolant substantially at saturation; condensing at least a secondportion of the compressed vapor coolant to generate condensed coolant;expanding the condensed coolant to approximately a saturation pressureof the condensed coolant to generate expanded coolant; and performing aprocess selected from the group consisting of: recycling at least afirst portion of the expanded coolant, wherein the first portion of theexpanded coolant comprises at least a portion of the vapor-containingcoolant; and mixing at least a second portion of the expanded coolantwith the coolant substantially at saturation prior to the introducing,wherein the collecting the vapor-containing coolant includes collectingthe partially evaporated coolant draining from the outlet of thechamber.